Currently, commonly used liquid crystal displays are thin film transistor liquid crystal displays. Thin film transistors may be classified into amorphous silicon thin film transistors, polycrystalline silicon thin film transistors, and oxide semiconductor thin film transistors based on materials of active layers. Oxide semiconductor thin film transistors have been widely used in liquid crystal displays due to their advantages such as simple manufacturing process, high electron mobility and the like.
Currently, a process of manufacturing an oxide semiconductor thin film transistor may include: a first step of forming a gate metal layer and forming a pattern including a gate electrode through a patterning process; a second step of forming a gate insulation layer on the gate electrode; a third step of forming an oxide semiconductor layer and forming a pattering including an active layer through a patterning process; and a fourth step of forming a source and drain metal layer on the active layer and forming a pattern including a source electrode and a drain electrode through a patterning process.
In the fourth step, an acidic etching solution needs to be used to etch the source and drain metal layer so as to form the pattern including the source electrode and the drain electrode, therefore, in the etching process, a region of the active layer being used as a channel is directly exposed to the acidic etching solution, thereby this region may be corroded by the acidic etching solution, and in turn, electrical properties of the oxide semiconductor thin film transistor may be adversely affected.
To solve this problem, there is a solution, where an etching stop layer is formed on the active layer, then a source and drain metal layer is formed, then the source and drain metal layer is subjected to a wet etching to form a source electrode and a drain electrode. In this manner, the problem of the region of the active layer used as a channel being corroded during forming the source electrode and the drain electrode through etching may be solved. In this solution, however, the source electrode and the drain electrode need to be connected to the active layer though via-holes formed in the etching stop layer. Due to restriction from process of forming the via-holes, a distance between a source electrode and a drain electrode is relatively large in prior art, such that the channel has a relatively large length, which is disadvantageous to improve electrical properties of the oxide semiconductor thin film transistor, and the oxide semiconductor thin film transistor may have relatively large sizes, which is disadvantageous for improving aperture ratio and resolution of a display device.
Therefore, there needs a manufacturing method which may prevent an active layer from being corroded and will not degrade electrical properties of an oxide semiconductor thin film transistor.